In U.S. Pat. No. 4,720,860, issued Jan. 19, 1988, and in U.S. Pat. No. 4,885,778, issued Dec. 5, 1989, systems are disclosed which permit the secure verification of an individual by providing the individual with a card displaying a unique nonpredictable or pseudorandom code for the individual which code changes at regular time intervals, for example each minute. With this system, the individual either (a) keys in the number appearing on his card and the system identifies the individual by recognizing this number as being one which is present for an identifyee in the system at the given instant; or (b) the system provides verification by having the individual key in his personal identification number (PIN) or a public ID number which the system then uses to retrieve the nonpredictable code which should be present for the individual in the system. In an improved version of the system, described in copending application Ser. No. 07/341,932, filed Apr. 21, 1989, a personal password or personal identification number (PIN) is entered into the card by the user keying a keypad on the card and this PIN is utilized in generating the nonpredictable code. This further enhances security in that it makes it more difficult for someone other than the person to whom the card was issued to use the card, (requires two factors rather than only a single factor for security; something known and something possessed rather than only something possessed) and it also results in the PIN being transmitted to the verification station in a secure coded fashion so that the PIN cannot be surreptitiously observed, electronically eavesdropped or learned.
While the systems described in these patents and applications provide a high level of security, they require that the user key in the number appearing on the card, which may be a five to ten digit number, in order to obtain identification or verification. While this is useful when the user is at a remote location, for example to gain access to a computer system by telephone or terminal, it can cause annoying delays when the user is for example trying to enter a physically secure facility where the user may have to enter his code three or four times to pass through various security barriers or checkpoints at the facility. It would therefore be desirable if the nonpredictable code could be available on a card, badge or other suitable device or unit carried by the user and be presented such that the code could be automatically sensed or read by the system, permitting the user to pass through various checkpoints without the need for keying in the current code appearing on the unit at each such location. It would also be desirable if the location of an individual in the facility could be tracked without requiring any active input on the part of the user.
While devices are currently available which permit a coded output to be obtained from a unit, these systems are used primarily for nonsecure applications such as identifying livestock, railroad cars, pallets or trucks. An example of such devices is the Nedap GIS RF identification system available from Nedap USA, Sunnyvale, Calif. Someone either gaining possession of such a device or capturing its electronic radiation could easily determine the code stored therein and surreptitiously generate such code. Any individual in possession of such device could also gain access to the facility even if such individual were not the individual to whom the unit was issued.
A need therefore exists for an improved identification and verification method and apparatus which provides highly secure identification and verification while permitting such verification or identification to be achieved with either no user input, or with the user inputting only a few, usually memorized, secret code characters, such as his PIN. If a PIN is entered, it is desirable that it need be entered only once to gain full access to the facility rather than being entered for each checkpoint, provided access is completed within a predetermined time period.